Multiple step methods for forming comformal layers

ABSTRACT

A two-step formation process provides conformal coverage at both the bottom surface and one or more side walls of an opening for various applications, e.g., high aspect ratio contact liners or storage cell capacitor electrode applications, and provides conformal coverage on any features requiring such coverage. A method for forming a conformal layer in the fabrication of integrated circuits includes providing a substrate assembly including at least a generally horizontal first surface and a second surface extending therefrom. A first portion of the layer is formed selectively on the horizontal first surface during a first period of time and a second portion of the layer is deposited selectively on the second surface during a second period of time. Further, one illustrative process for forming tungsten nitride in the fabrication of integrated circuits includes forming tungsten nitride on the horizontal first surface during a first period of time and depositing tungsten nitride on the second surface during a second period of time by plasma enhanced chemical vapor deposition. The tungsten nitride may be formed on the first surface by plasma enhanced chemical vapor deposition using a first reactant gas mixture including WF 6 , at least one of NF 3  and N 2 , and H 2  with the tungsten nitride being deposited on the second surface by plasma enhanced chemical vapor deposition using a second reactant gas mixture including WF 6 , at least one of NF 3  and N 2 , H 2 , and He.

FIELD OF THE INVENTION

[0001] The present invention relates to the formation of layers, e.g.,tungsten nitride layers, in the fabrication of semiconductor devices.More particularly, the present invention pertains to the formation ofsuch layers to achieve conformal coverage on features.

BACKGROUND OF THE INVENTION

[0002] In the fabrication of integrated circuits, various layers, e.g.,conductive layers and insulative layers, are used. For example, duringthe formation of semiconductor devices, such as dynamic random accessmemories (DRAMs), static random access memories (SRAMs),microprocessors, etc., insulating layers are used to electricallyseparate conductive layers such as doped polycrystalline silicon, dopedsilicon, aluminum, refractory metal suicides, etc. It is often requiredthat the conductive layers be interconnected through holes or openingsin the insulating layer. Such holes are commonly referred to as contactholes, i.e., when the hole extends through an insulating layer to anactive device area, or vias, i.e., when the hole extends through aninsulating layer between two conductive layers.

[0003] The profile of an opening is of particular importance such thatspecific characteristics are achieved when a contact hole or via isprovided or filled with a conductive material. For example, many holesare high aspect ratio holes or openings. In many cases, where openingsare high aspect ratio openings, it is difficult to form certainmaterials within the openings. For example, in the formation of tungstennitride on both the bottom and side walls defining an opening usingconventional tungsten nitride formation techniques, poor step coverageresults.

[0004] Tungsten nitride is a preferably used material for formation ofbarriers in the fabrication of semiconductor devices to prevent thediffusion of one material to an adjacent material. For example, whenaluminum contacts silicon surfaces, spiking can occur, and when aluminumcomes into direct contact with tungsten, a highly resistive alloy isformed. Further, for-example, copper diffusion in silicon occurs whensuch materials are in direct contact. Diffusion barriers, e.g., tungstennitride barriers, are commonly used to prevent such undesirablereactions. Tungsten nitride is preferably used in such diffusion barrierapplications as it has low resistivity and is thus suitable for use inconductive interfaces for high speed applications. Further, tungstennitride is also thermally stable, making it more suitable for hightemperature processing which is common in integrated circuit fabricationtechniques.

[0005] Conductive materials are also used in the formation of storagecell capacitors for use in semiconductor devices, e.g., DRAMs. Storagecapacity and size are important characteristics of a storage cell. Oneway to retain the storage capacity of a device and decrease its size isto increase the dielectric constant of the dielectric layer of thestorage cell capacitor. Therefore, high dielectric constant materialsare used in such applications interposed between two electrodes. One ormore layers of various conductive materials may be used as the electrodematerial. However, generally, one or more of the layers of conductivematerials must have certain barrier properties and oxidation resistanceproperties, particularly due to the processes used in forming highdielectric constant materials. Tungsten nitride is a material thatresists oxidation and provides very good barrier properties as describedabove. As such, tungsten nitride is advantageously used as an electrodematerial for a storage cell capacitor.

[0006] However, many storage cell capacitors are formed by processesincluding high aspect ratio openings. For example, in U.S. Pat. No.5,392,189 to Fazan, et al., entitled “Capacitor Compatible with HighDielectric Constant Materials Having Two Independent Insulative Layersand the Method for Forming Same,” issued Feb. 21, 1995, a storage cellcapacitor is provided wherein electrodes are formed of a conductivematerial within high aspect ratio openings having a bottom surface andside walls. As previously described, conventional tungsten nitrideformation processes generally have poor step coverage and, therefore,conventional methods for forming tungsten nitride in high aspect ratioopenings for electrodes of storage cell capacitors is inadequate. Forexample, in conventional PECVD processing, tungsten nitride is depositedwith thicknesses greater on bottom surfaces than on side wall surfacesdefining high aspect ratio openings.

[0007] Various methods for forming tungsten nitride are known anddescribed. However, such methods do not provide the conformal coverageadequate for various applications. Particularly, such conformal coverageis lacking, for example, in applications wherein tungsten nitride isformed relative to high aspect ratio openings, e.g., contact and viaopenings, certain storage cell capacitor structures, etc.

[0008] For example, one method of forming tungsten nitride is withchemical vapor deposition (CVD). Generally, for example, conventionalchemical vapor deposition processes react WF₆, N₂, and H₂ at a hightemperature forming WN_(x) and HF. Problems attendant to this processinclude the detrimental tendency of the fluorine to attack exposedsurfaces of the semiconductor wafers on which the tungsten nitride isbeing formed and problems generally associated with high temperatures.

[0009] Another method of forming tungsten nitride is by physical vapordeposition (PVD). Conventional PVD technology involves reactivesputtering from a tungsten target in an atmosphere of gaseous nitrogenwith an argon carrier gas. Conventional PVD processes may result in afilm deposited on the bottom surface defining a high aspect ratioopening. However, it is inadequate for formation of tungsten nitride onside walls of such openings.

[0010] Further, as described in U.S. Pat. No. 5,487,923 to Min et al.,entitled “Method for Depositing Tungsten Nitride Thin Films forFormation of Metal Wirings of Silicon Semiconductor Elements,” issuedJan. 30, 1996, a plasma enhanced chemical vapor deposition (PECVD)process for formation of tungsten nitride is described. As describedtherein, the deposition of the tungsten nitride thin film is carried outusing a WF₆, H₂, and NH₃ reactant gas mixture. Various parameters forthe PECVD process are described. However, such a PECVD process does notprovide for adequate conformal and uniform coverage in small high aspectratio openings. Also, it is known that adducts, such as WN_(x)NH_(y)form during reactions containing NH₃. Such adducts are solid in form andcause particle problems.

[0011] Further, various other layers, e.g., insulating layers such assilicon dioxide or silicon nitride, are in many circumstances depositedon features having steps requiring conformal coverage, e.g., capacitorstructures. Various conventional methods for depositing such layers donot provide for adequate conformal and uniform coverage for suchfeatures in such circumstances. For example, in conventional CVD methodsfor depositing silicon nitride over stepped features, more siliconnitride may be deposited on sidewalls than on lower surfaces from whichsuch walls extend depending upon the parameters of the CVD process.

SUMMARY OF THE INVENTION

[0012] To overcome the problems described above, and others which willbe apparent from the detailed description below, a two-step formationprocess to provide conformal coverage at both the bottom surface and oneor more side walls of a opening for various applications, e.g., highaspect ratio contact liners or storage cell capacitor electrodeapplications, or to provide conformal coverage on any features requiringsuch coverage, e.g. top electrode of a capacitor, is described. Thetwo-step process provides for conformal step coverage in such variedapplications.

[0013] A method for forming a conformal layer in the fabrication ofintegrated circuits according to the present invention includesproviding a substrate assembly including at least a generally horizontalfirst surface and a second surface extending therefrom. A first portionof the layer is formed selectively on the horizontal first surfaceduring a first period of time and a second portion of the layer isdeposited selectively on the second surface during a second period oftime.

[0014] In various embodiments of the method, the layer may be aninsulative layer or a conductive layer, an opening may be defined atleast in part by the first and second surfaces wherein the opening is asmall high aspect ratio opening having an aspect ratio greater thanabout 1 and a critical dimension of less than about 1 micron, thedeposition of the second portion of the layer selectively on the secondsurface may include providing a reactant gas mixture and subjecting thereactant gas mixture to a glow discharge created by applying anelectromagnetic field across the reactant gas mixture, and the formationof the first portion of the layer selectively on the first surface maybe performed before or after the deposition of the second portion of thelayer selectively on the second surface.

[0015] A method for forming tungsten nitride in the fabrication ofintegrated circuits according to the present invention includesproviding a substrate assembly with a generally horizontal first surfaceand a second surface extending therefrom. Tungsten nitride is formed onthe horizontal first surface during a first period of time and tungstennitride is deposited on the second surface during a second period oftime by plasma enhanced chemical vapor deposition.

[0016] In one embodiment of the method, tungsten nitride is formed onthe first surface by plasma enhanced chemical vapor deposition using afirst reactant gas mixture including WF₆, at least one of NF₃ and N₂,and H₂. The tungsten nitride is deposited on the second surface byplasma enhanced chemical vapor deposition using a second reactant gasmixture including WF₆, at least one of NF₃ and N₂, H₂, and He. Further,the partial pressure of WF₆ and the at least one NF₃ and N₂ used indepositing tungsten nitride on the second surface during the secondperiod of time is in the range of about 1.5 times to about 20 times thepartial pressure of WF₆ and the at least one NF₃ and N₂ used indepositing the tungsten nitride on the first surface during the firstperiod of time.

[0017] In another embodiment of the method, tungsten nitride isdeposited on the second surface during the second period of time byplasma enhanced chemical vapor deposition using a gas mixture includingWF₆, at least one of NF₃ and N₂, H₂, and He. The partial pressure of WF₆and the at least one of NF₃ and N₂ is in a range of about 0.1 percent toabout 20 percent of the total pressure. Further, the deposition may beperformed at a substrate temperature in a range of about 200° C. toabout 500° C.

[0018] In another method according to the present invention, a conformallayer of tungsten nitride is formed in an opening defined by a bottomsurface and at least one side wall extending therefrom. The methodincludes depositing tungsten nitride on at least the bottom surface byplasma enhanced chemical vapor deposition using a first gas mixtureincluding WF₆, at least one of NF₃ and N₂, and H₂. The method furtherincludes depositing tungsten nitride on at least the side wall by plasmaenhanced chemical vapor deposition using a second reactant gas mixtureincluding WF₆, at least one of NF₃ and N₂, H₂, and He.

[0019] In one embodiment of the method, the partial pressure of WF₆ andthe at least one NF₃ and N₂ used in depositing tungsten nitride on theat least one side wall is in a range of about 0.1 percent to about 20percent of the total pressure and the partial pressure of He is in arange of about 0.5 percent to about 50 percent of the total pressurewhen depositing tungsten nitride on the at least one side wall.

[0020] In other methods according to the present invention, the two stepmethod of forming a conformal layer is used in a variety ofapplications, for example, in small high aspect ratio openings, in theformation of an electrode for a capacitor, in formation of aninterconnect structure, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be better understood from reading thefollowing description of illustrative embodiments with reference to theattached drawings, wherein below:

[0022] FIGS. 1A-1D generally illustrate a two-step formation process,e.g., a two-step tungsten nitride process, according to the presentinvention.

[0023] FIGS. 2A-2D illustrate the use of a method according to thepresent invention in a storage cell capacitor application.

[0024] FIGS. 3A-3D show use of a method according to the presentinvention in a contact application.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention shall be described generally with referenceto FIGS. 1A-1D. Thereafter, embodiments and illustrations ofapplications using the present invention shall be described withreference to FIGS. 2A-2D and FIGS. 3A-3D. It will be apparent to oneskilled in the art that scaling in the figures does not representprecise dimensions of the various elements illustrated therein.

[0026] FIGS. 1A-1D illustrate the two-step method of forming a conformallayer of material 40 (FIG. 1D), e.g., tungsten nitride, on a substrateassembly 10 according to the present invention. As shown in FIG. 1A,substrate assembly 10 includes a first portion 11 and a second portion12. Second portion 12 is formed on first portion 11 and includes anopening 14 defined therein by a bottom surface 16 of first portion 11and one or more side walls of second portion 12. Bottom surface 16 is agenerally horizontal surface from which the one or more side walls 20extend. The side walls 20 may be substantially orthogonal to thehorizontal bottom surface 16 as shown in FIG. 1A or may be at any otherdesired angle for forming a desired opening 14 in second portion 12.Second portion 12 further includes a horizontal upper surface 18generally parallel to bottom surface 16. The one or more side walls 20and the generally horizontal upper surface 18 of second portion 12 sharean edge or corner 22. Likewise, the one or more side walls 20 also forma corner or edge 21 with the bottom surface 16.

[0027] As used in this application, “substrate assembly” refers toeither a semiconductor substrate such as the base semiconductor layer,e.g., the lowest layer of silicon material in a wafer, or a siliconlayer deposited on another material such as silicon on sapphire, or asemiconductor substrate having one or more layers or structures formedthereon or regions formed therein. When reference is made to a substrateassembly in the following description, various process steps may havebeen previously used to form or define regions, junctions, variousstructures or features, and openings such as vias, contact openings,high aspect ratio openings, etc.

[0028] For example, second portion 11 of substrate assembly 10 may be astructure upon which a capacitor is formed with the second portion 12 ofthe substrate assembly 10 being an insulative layer such as an oxidelayer, e.g., silicon dioxide, BPSG, PSG, etc. As such, opening 14defined in substrate assembly 10 by bottom surface 16 and the one ormore side walls 20 includes surfaces upon which a bottom electrode of astorage cell capacitor is formed such as described with reference toFIGS. 2A-2D.

[0029] Further, for example, the first portion 11 of substrate assembly10 may include a source and/or drain region to which a contact is to bemade through an insulative layer 12. As such, opening 14 defined bybottom surface 16 and the one or more side walls 20 is a contact openingto a region to be interconnected using a conductive material depositedaccording to the present invention, such as described with reference toFIGS. 3A-3D herein.

[0030] Further, for example, the substrate assembly 10 may include anystructure upon which a conformal insulative layer is to be deposited.For example, the structure may include a stepped feature such as anisolation trench or any other feature upon which a conformal layer isdesired.

[0031] The two-step method according to the present invention may beused for any application requiring conformal layer formation, e.g.,conformal layers of conductive materials such as tungsten nitride orinsulative layers such as silicon dioxide layers or other oxide layers.However, the present invention is particularly beneficial for providingconformal coverage of tungsten nitride on surfaces of features, e.g.,step coverage at both the bottom surface and one or more side wallsurfaces defining small high aspect ratio openings such as contact holesor vias through an oxide insulating layer to an underlying material,trenches, openings for formation of cell electrodes, etc. As such, oneskilled in the art will recognize that the two-step formation method maybe used to form any insulative or conductive layer, e.g., tungstennitride, on any surface areas requiring uniform and conformal layers. Asused herein, conformal coverage refers to providing a generally uniformlayer of material on a surface in the same shape as the surface, i.e.,the surface of the layer and the surface being covered are generallyparallel. One skilled in the art will recognize, of course, that theterm “generally” is used to allow for acceptable tolerances.

[0032] As described herein, small high aspect ratio openings havefeature sizes or critical dimensions below about 1 micron (e.g., such asdiameter or width of an opening being less than about 1 micron) and mayhave critical dimensions below about 0.5 microns and even below about0.3 microns. Such small high aspect ratio openings have aspect ratiosgreater than about 1 and may further have aspects ratios greater thanabout 5 and even greater than 20. Such critical dimensions and aspectratios are applicable to contact holes, vias, trenches, and any otherconfigured openings. For example, a trench having an opening width of 1micron and a depth of 3 microns has an aspect ratio of 3. Further, forexample, where line spacing is 0.22 microns, the present inventionprovides desirable conformal step coverage within a high aspect ratioopening.

[0033] Although the present invention is more specifically describedbelow with respect to the deposition of tungsten nitride, the presentinvention is applicable to the formation of any conformal layer using amultiple step process wherein a portion of a layer is selectively formedon a generally horizontal surface during one process step and furtherportions of the layer are selectively formed on other surfaces extendingfrom the horizontal surface, e.g., side wall, during one or more otherprocess steps. In other words, at least two process steps performedduring different time periods are used to deposit a conformal layer overa substrate assembly surface. The conformal layer deposited may beinsulative or may be conductive. For example, the multiple step processmay be used to deposit a conformal oxide layer, e.g., a silicon dioxidelayer using silane and nitrous oxide or a tetraethylorthosilicate (TEOS)oxide layer using oxygen and TEOS. Further, for example, a siliconnitride layer may be deposited using silane and ammonia. Further,conductive layers, such as titanium nitride, tungsten nitride or anyother conductive layer that may be difficult to conformally deposit onfeatures, e.g., high aspect ratio openings, may be deposited accordingto the multiple step process described herein.

[0034] It will be readily apparent to one skilled in the art that themultiple step process allows each process step to be tailored forachieving selective deposition on the portion of the substrate assemblysurface desired. For example, deposition of a material selectively on agenerally horizontal surface may require different process parametersthan deposition of such material selectively on a surface extendingtherefrom, e.g., a generally vertical surface. Such different processparameters and method steps for performing such selective deposition isillustrated below with respect to tungsten nitride, but one skilled inthe art will recognize that the controllable process steps for achievingselective deposition of materials on features, e.g., stepped features,is equally applicable to other materials. As used herein, forming amaterial selectively on a surface refers to selectively depositing thematerial to a much greater degree on one particular portion of a surfacerelative to other portions of the surface; however, a small amount ofmaterial may form on the other portions of the surfaces. For example, asshown in FIG. 1B, material is selectively formed on the horizontalsurfaces of the substrate assembly with only little formation of thematerial on the sidewalls proximate the corners.

[0035] The formation of tungsten nitride according to the presentinvention shall be described using the illustration of FIGS. 1A-1D. Theprocess includes a first step of forming tungsten nitride on at leastthe generally horizontal surfaces during a first time period, e.g.,surface 16 at the bottom of opening 14 and surfaces 18 at the upperportion of substrate assembly 10 as shown in FIG. 1B. A second step ofthe tungsten nitride formation method includes forming tungsten nitrideselectively on at least the side walls 20 defining the opening 14 asshown in FIG. 1C. The resulting structure of a conformal uniformtungsten nitride layer 40 over substrate assembly 10 is shown in FIG.1D.

[0036] One skilled in the art will recognize that the steps of thesequential multiple step process may be performed in any order. Forexample, the formation of tungsten nitride on the one or more side walls20 may be performed prior to the formation of tungsten nitride on thegenerally horizontal surfaces including bottom surface 16. However,preferably, the tungsten nitride is formed first on bottom surface 16and the other generally horizontal surfaces, and thereafter, thetungsten nitride is formed on the one or more side walls 20.

[0037] In the first step of the illustrative tungsten nitride formationmethod, as shown in FIG. 1B, tungsten nitride is formed over at leastthe horizontal surface areas of the substrate assembly 10. For example,tungsten nitride region 24 is formed on bottom surface 16 definingopening 14 and tungsten nitride regions 26 are formed on upperhorizontal surfaces 18. Further, tungsten nitride may form adjacentcorner or edge 22 on the one or more side walls 20. However, tungstennitride is not formed conformally on the one or more side walls 20.

[0038] The tungsten nitride formed on the generally horizontal surfaces,e.g., bottom surface 16 and upper surfaces 18, may be formed by one ormore various processes. For example, the formation of such tungstennitride material 24, 26, and 28 on the generally horizontal surfaces maybe formed by sputtering from a tungsten nitride deposition target orfrom a tungsten deposition target in a nitrogen atmosphere. For example,at least one illustration of such physical vapor deposition of tungstennitride is described in U.S. Pat. No. 5,633,200 to Hu, entitled “Processfor Manufacturing a Large Grain Tungsten Nitride Film and Process forManufacturing a Lightly Nitrided Titanium Salicide Diffusion Barrierwith a Large Grain Tungsten Nitride Cover Layer,” issued May 27, 1997.Further, such tungsten nitride regions 24, 26, 28 may be deposited bychemical vapor deposition, e.g., atmospheric, low pressure, or plasmaenhanced chemical vapor deposition (PECVD). Preferably, the formation oftungsten nitride on the generally horizontal surfaces, e.g., bottomsurface 16 and upper surfaces 18, is performed by PECVD.

[0039] The steps according to the present invention using plasmaenhanced chemical vapor deposition are carried out in a plasma enhancedchemical vapor deposition reactor, such as a reaction chamber availablefrom Genus, Inc., Applied Materials, Inc., or Novelus, Inc. However, anyreaction chamber suitable for performing PECVD may be used.

[0040] In PECVD processes, the reactant gases are introduced into thereaction chamber which is at low pressure (i.e., low compared to ambientpressure). The reaction chamber is evacuated by means of vacuum pumps toremove undesirable reactive species, such as oxygen. Then, a reactantgas mixture including the reactant gases are admitted into the chamber.This is accomplished by one of various techniques. For example, theintroduction into the chamber may be accomplished with the use ofcompounds which are gases at room temperature or by heating a volatilecompound and bubbling a gas through it to carry it into the reactionchamber. It should be readily apparent that the techniques used forintroduction of the compounds into the chamber may be varied and thatthe present invention is not limited to any particular technique.Typically, the reactant gases are admitted at separate inlet ports. Inaddition to the reactive compound, a dilution gas may be flowed into thechamber. For example, argon may be flowed through the chamber at avaried flow rate. In PECVD, a plasma is created by applying an electricfield across the reactant gas mixture containing the reactant gases. Asused herein, PECVD includes the use of any created plasma including highdensity plasmas. A high density plasma is a plasma having a density ofabout 10¹¹ ions/cm³ to about 10¹³ ions/cm³. The plasma adds energy tothe reaction to drive the reaction to completion. Generally, use of aplasma process allows the substrate assembly to be kept at a somewhatlower temperature than other CVD processes. Any suitable power sourcemay be used to generate the plasma in the reaction chamber. Suitablepower sources include an RF generator, a microwave (e.g., 2.5 GHzmicrowave source) generator, or an electron cyclotron resonance (ECR)source. A preferred power source is an RF generator operating as astandard 13.56 MHz source.

[0041] For example, in the deposition of tungsten nitride the reactantgases would include a tungsten containing gas and a nitrogen containinggas. An RF generator would supply power between a substrate holder inthe chamber holding a wafer and the reaction chamber, thus creating aplasma in the region above the wafer upon which the tungsten nitride isto be deposited. The reactant gases begin to react inside the reactionchamber as they are absorbed at the heated surface of the wafer. Thewafer is heated, for example, by a resistively heated susceptor, byconvection from a substrate holder (such as graphite or alumina) that isheated to a preferred temperature via a lamp source, or any otherheating method. A chemical reaction occurs, thereby depositing a layerof tungsten nitride on the surface of the wafer.

[0042] Preferably, in accordance with the present invention, to formtungsten nitride on the generally horizontal surfaces, e.g., bottomsurface 16, WF₆ and at least one of NF₃ and N₂ are introduced into thereaction chamber, such as via flow meters. Further, H₂ as a reducing gasis introduced into the reaction chamber. Yet further, an inert gas, suchas argon or helium, may be supplied to the reaction chamber as adilution gas to change the total gas flows thereto and the partialpressures within the reaction chamber. Any inert gas that is nonreactivewith the reactant gases may be used. In the reaction chamber, thereactant gas mixture is preferably subjected to a glow discharge orplasma created by applying a radio frequency electromagnetic field of13.56 megahertz at a power density of about 0.1 W/cm² to about 2 W/cm²across the reactant gas mixture.

[0043] Preferably, the reactant gas mixture is such that the partialpressure of the tungsten and nitrogen containing reactant gases (i.e.,WF₆ and at least one of NF₃ and N₂) have a partial pressure of about 0.5percent to about 50 percent of the total pressure. Preferably, thepartial pressure of the tungsten and nitrogen containing reactant gases(i.e., WF₆ and at least one of NF₃ and N₂) is in the range of about 1percent to about 10 percent of the total pressure.

[0044] In the reaction chamber, the deposition pressure is maintained ata lower pressure in the range of about 0.1 torr to about 30 torr.Preferably, the deposition pressure is in the range of about 0.3 torr toabout 3 torr. Further, the wafer or substrate temperature is maintainedat a lower temperature of about 200° C. to about 500° C. Morepreferably, the temperature is in the range of about 250° C. to about400° C., and yet more preferably, the temperature is in the range ofabout 250° C. to about 350° C. By reducing the temperature and totalpressure during the deposition of tungsten nitride on the generallyhorizontal surfaces, including bottom surface 16, bottom step coverageis improved. For example, a layer of tungsten nitride 24 is formed onbottom surface 16 adjacent the one or more side walls 20.

[0045] To further enhance the deposition of tungsten nitride on thebottom surface 16 and other generally horizontal surfaces, e.g., uppersurfaces 18, during PECVD, a bias may be applied to the wafer upon whichthe tungsten nitride is being deposited to make the tungsten nitridedeposition more directional. In other words, the bias provides for moreuniformity in a vertical direction. For example, a bias may be providedby applying a 0 to 200 volt RF source to the wafer or substrate holderhaving the wafer positioned thereon.

[0046] After formation of tungsten nitride according to the first stepduring a first time period, the resultant structure is as shown in FIG.1B. Thereafter, in a second step of the tungsten nitride formationprocess, tungsten nitride is deposited on the one or more side walls ofthe opening 14 by PECVD during a second period of time, as illustratedin FIG. 1C. The tungsten nitride deposition during the second timeperiod on the one or more side walls 20 of opening 14 may be performedin the same reaction chamber as the deposition of tungsten nitride onthe generally horizontal surfaces or may be performed in a completelydifferent reaction chamber.

[0047] In the second step, by introducing helium into the reactionchamber with the other reactant gases and increasing the partialpressure of the tungsten and nitrogen containing reactant gases (i.e.,WF₆ and at least one of NF₃ and N₂) relative to the total pressure,conformal coverage of the side walls 20 is improved. Preferably, toprovide conformal coverage of the surfaces extending from the bottomsurface 16, e.g., side walls 20, WF₆, at least one of NF₃ and N₂, H₂,and He are introduced into the reaction chamber, for example, via flowmeters. As indicated previously, an inert dilution gas may be introducedto the reaction chamber which will change the total gas flow and partialpressures. In the reaction chamber, the reactant gases are preferablysubjected to a glow discharge or plasma created by applying a radiofrequency electromagnetic field of 13.56 megahertz at a power density of0.1 W/cm² to 2 W/cm² across the reactant gas mixture.

[0048] Preferably, for achieving conformal coverage on the one or moreside walls 20 defining opening 14, the partial pressure of the tungstenand nitrogen containing reactant gases (i.e., WF₆ and at least one ofNF₃ and N₂) is in the range of about 0.1% to about 20% of the totalpressure. Preferably, the partial pressure of the tungsten and nitrogencontaining reactant gases (i.e., WF₆ and at least one of NF₃ and N₂) isabout 1% to about 10% of the total pressure. Further, the partialpressure of He in the reaction chamber is in the range of about 0.5percent to about 50 percent. More preferably, the partial pressure ofhelium in the reaction chamber is in the range of about 5 percent toabout 20 percent.

[0049] The step of forming tungsten nitride on the one or more sidewalls 20 is preferably performed in the reaction chamber at a substratetemperature in the range of about 200° C. to about 500° C. Morepreferably, the temperature is in the range of about 300° C. to about400° C. Yet further, the deposition pressure in the reaction chamber isin the range of about 0.1 torr to about 30 torr. More preferably, thedeposition pressure is in the range of about 0.3 torr to about 3 torr.

[0050] When comparing the partial pressures of the tungsten and nitrogencontaining reactant gases in the first step to the second step, it ispreferred that the partial pressure of the tungsten and nitrogencontaining reactant gases (i.e., WF₆ and at least one of NF₃ and N₂)used in depositing the tungsten nitride on the one or more side wallsurfaces 20 is in the range of about 1.5 times to about 20 times thepartial pressure of the tungsten and nitrogen containing reactant gases(i.e., WF₆ and at least one of NF₃ and N₂) used in depositing thetungsten nitride on the generally horizontal surfaces, e.g., bottomsurface 16. Preferably, the partial pressure of the tungsten andnitrogen containing reactant gases (i.e., WF₆ and at least one of NF₃and N₂) used in depositing tungsten nitride on the one or more sidewalls 20 is in the range of about 2 times to about 10 times the partialpressure of the tungsten and nitrogen containing reactant gases (i.e.,WF₆ and at least one of NF₃ and N₂) used in depositing the tungstennitride on the bottom surface 16 or generally horizontal surfaces.

[0051] One skilled in the art will recognize that alternative plasmaenhanced processes may be used for performing the tungsten nitridedeposition under similar two step processes and similar parameters asdescribed above with regard to the preferred processes. For example, oneplasma enhanced process may use the reactant gases including WF₆, Si₄,N₂, H₂ or alternatively, use the reactant gases including WCl₆, Si₄, N₂,H₂.

[0052] As shown in FIG. 1C, deposition of tungsten nitride during thesecond step of the formation process used to deposit tungsten nitride onthe one or more side walls 20 results in some additional deposition onthe generally horizontal surfaces. For example, tungsten nitride regions30 are formed adjacent the one or more side walls 20, tungsten nitrideregion 34 is formed over the previously formed tungsten nitride materialon the bottom surfaces defining the opening 14, as well as tungstennitride regions 32 being formed over the tungsten nitride previouslydeposited over the top surfaces 18. Resulting from the two-step tungstennitride formation process according to the present invention is thelayer 40 as shown in FIG. 1D. The thickness of the tungsten nitridelayer is preferably in the range of about 50 Å to about 500 Å. Morepreferably, the thickness of the tungsten nitride layer 40 is in therange of about 100 Å to about 500 Å. There may be a slight variation inthe thickness of the tungsten nitride material deposited on the one ormore side walls 20 relative to the bottom surface 16. However,generally, the conformal tungsten nitride layer 40 will have a uniformthickness ±200 Å, preferably ±50 Å.

[0053] Two illustrations of using the above described tungsten nitrideformation method are described below with reference to FIGS. 2A-2D andFIGS. 3A-3D. The use of the formation method according to the presentinvention is described with reference to FIGS. 2A-2D wherein tungstennitride is used for one or both of the electrodes of a high dielectriccapacitor of a storage cell. Further, the tungsten nitride formationmethod according to the present invention is described with reference toFIGS. 3A-3D wherein a contact liner of tungsten nitride is described.For simplicity purposes, the illustrative descriptions are limited tothe use of a tungsten nitride layer described in these two illustrativestructures. There are other semiconductor processes and structures forvarious devices, e.g., CMOS devices, memory devices, etc., that wouldbenefit from the present invention and in no manner is the presentinvention limited to the illustrative embodiments described herein,e.g., contact liner and electrode structure. The tungsten nitrideformation method may be used with any surface area requiring aconforming tungsten nitride layer.

[0054] As shown in FIG. 2A, a device structure 100 is fabricated inaccordance with conventional processing techniques through the formationof an opening 184. Such processing is performed prior to depositing abottom electrode structure on the surfaces defining the opening 184using the tungsten nitride formation method in accordance with thepresent invention. As such, and as further described in U.S. Pat. No.5,392,189 to Fazan et al., the device structure 100 includes field oxideregions 105 and active regions, i.e., those regions of the substrate 107not covered by field oxide. A word line 121 and a field effecttransistor (FET) 122 is formed relative to the field oxide region 105 inthe active regions. Suitable source/drain regions 125, 130 are createdin silicon substrate 107. An insulative conformal layer of oxidematerial 140 is formed over regions of FET 122 and word line 121. Apolysilicon plug 165 is formed to provide electrical communicationbetween the substrate 107 and a storage cell capacitor to be formedthereover. Various barrier layers are formed over the polysilicon plug165, including layers 167 and 175. For example, such layers may betitanium nitride, tungsten nitride, or any other metal nitride which actas a barrier. For example, such a tungsten nitride layer may bedeposited in accordance with the present invention. Thereafter, anotherinsulative layer 183 is formed and an opening 184 is defined therein.

[0055] According to one embodiment of the present invention, a tungstennitride layer 109 is formed on bottom surface 185 and one or more sidewalls 186 defining opening 184. First, as shown in FIG. 2B, tungstennitride 103 is formed on the bottom surface 185 and upper surface 189 ofthe device structure 100. Thereafter, as shown in FIG. 2C, the secondstep of the tungsten nitride deposition method is used to form tungstennitride on the one or more side walls 186 defining opening 184. As shownin FIG. 2C, a uniform tungsten nitride layer 109 with conformal coverageis provided. Thereafter, as shown in FIG. 2D, the tungsten nitride layer109 is formed resulting in tungsten nitride layer 187 lining the opening184.

[0056] A dielectric layer 191 is then formed relative to the tungstennitride layer 187. For example, the dielectric layer may be any suitablematerial having a suitable dielectric constant such asBa_(x)Sr_((1−x))TiO₃[BST], BaTiO₃, SrTiO₃, PbTiO₃, Pb(Zr,Ti)O₃[PZT],(Pb,La)(Zr,Ti)O₃[PLZT], (Pb,La)TiO₃[PLT], KNO₃, and LiNbO₃.

[0057] Further thereafter, a second electrode 192 is formed relative tothe dielectric material 191. In one embodiment of the present invention,the second electrode 192 is also formed of tungsten nitride according tothe two step process as described herein and which shall not bedescribed in any further detail.

[0058] It will be recognized by one skilled in the art that either oneor both of the electrodes of a capacitor may be formed according to thepresent invention. If one of the electrodes is not formed of tungstennitride, it may be of any other conductive material generally used forcapacitor electrode structures. For example, such an electrode may be ofany conductive material such as platinum, titanium nitride, etc.Further, one skilled in the art will recognize that the tungsten nitridelayer may be one of several layers forming an electrode stack. With useof the present invention, either one or both electrodes of a capacitorcan be formed of tungsten nitride conformally formed of uniformthickness providing desired resistivity and barrier properties.

[0059] It will be recognized by one skilled in the art that anycapacitor having a surface whereupon tungsten nitride is to beconformally formed thereon will benefit from the present invention. Forexample, a container capacitor typically includes electrodes formed onsurfaces requiring conformal formation. Such a container capacitorstorage cell is described in U.S. Pat. No. 5,270,241 to Dennison et al.,entitled “Optimized Container Stacked Capacitor DRAM Cell UtilizingSacrificial Oxide Deposition and Chemical Mechanical Polishing,” issuedDec. 14, 1993.

[0060] As shown in FIG. 3A, device structure 200 is fabricated inaccordance with conventional processing techniques through the formationof contact opening 259 prior to metalization of the exposed contact area255 of substrate 207. As such, prior to metalization, the devicestructure 200 includes field oxide regions 205 and active areas, i.e.,those regions of the substrate 207 not covered by field oxide. Formedrelative to the field oxide regions 205 and the active areas are wordline 221 and field effect transistor 222. Suitably doped source/drainregions 225 and 230 are formed as known to one skilled in the art. Aconformal layer of oxide material 240 is formed thereover and contactopening 259 is defined therein to the exposed contact area 255 in dopedregion 230 of silicon substrate 207. Thereafter, one or moremetalization or conductive layers are formed in the contact opening 259for providing electrical connection to substrate region 230. Forexample, various materials may be formed in contact opening 259, such astitanium nitride or other diffusion barrier materials. Preferably, acontact liner 285 is formed of tungsten nitride deposited in accordancewith the present invention upon bottom surface 260 and generallyhorizontal upper surfaces 263 along with the one or more side walls 261defining the opening 259.

[0061] As shown in FIG. 3B, during the first step of the tungstennitride process, tungsten nitride regions 270 are formed on thegenerally horizontal surfaces including bottom surface 260, portions ofthe FET 222 and word line 221 and also upper surfaces 263. Thereafter, asecond step of the tungsten nitride deposition process is performedresulting in the uniform tungsten nitride layer 275 over all of thesurfaces including side walls 261 as shown in FIG. 3C. Upon removal ofportions of the layer, a liner 285 is formed within contact opening 259.Thereafter, a conductive material 276 is formed in the contact openingfor providing connection to doped region 230 of substrate 207.

[0062] All patents and references cited herein are incorporated in theirentirety as if each were incorporated separately. This invention hasbeen described with reference to illustrative embodiments and is notmeant to be construed in a limiting sense. As described previously, oneskilled in the art will recognize that various other illustrativeapplications may utilize the formation method as described herein toprovide a conformal and uniform layer relative to one or more surfaces.Various modifications of the illustrative embodiments, as well asadditional embodiments of the invention, will be apparent to personsskilled in the art upon reference to this description. It is thereforecontemplated that the appended claims will cover any such modificationsor embodiments that may fall within the scope of the present inventionas defined by the accompanying claims.

What is claimed is:
 1. A method for forming a conformal layer in thefabrication of integrated circuits, the method comprising: providing asubstrate assembly including at least a generally horizontal firstsurface and a second surface extending therefrom; forming a firstportion of the layer selectively on the horizontal first surface duringa first period of time; and depositing a second portion of the layerselectively on the second surface during a second period of time.
 2. Themethod of claim 1, wherein the layer is an insulative layer.
 3. Themethod of claim 1, wherein the layer is a conductive layer.
 4. Themethod of claim 1, wherein an opening is defined at least in part by thefirst and second surfaces, the opening being a small high aspect ratioopening having an aspect ratio greater than about 1 and a criticaldimension of less than about 1 micron.
 5. The method of claim 1, whereindepositing the second portion of the layer selectively on the secondsurface includes providing a reactant gas mixture and subjecting thereactant gas mixture to a glow discharge created by applying anelectromagnetic field across the reactant gas mixture.
 6. The method ofclaim 1, wherein forming the first portion of the layer selectively onthe first surface is performed after the depositing of the secondportion of the layer selectively on the second surface.
 7. A method forforming tungsten nitride in the fabrication of integrated circuits, themethod comprising: providing a substrate assembly including at least agenerally horizontal first surface and a second surface extendingtherefrom; forming tungsten nitride on at least the horizontal firstsurface during a first period of time; and depositing tungsten nitrideon at least the second surface during a second period of time by plasmaenhanced chemical vapor deposition.
 8. The method of claim 7, whereinforming tungsten nitride on at least the horizontal first surfaceincludes depositing the tungsten nitride on the first surface by plasmaenhanced chemical vapor deposition.
 9. The method of claim 8, whereindepositing tungsten nitride on the second surface during the secondperiod of time includes depositing the tungsten nitride on the secondsurface by plasma enhanced chemical vapor deposition using a reactantgas mixture including helium.
 10. The method of claim 8, wherein formingtungsten nitride on the first surface includes depositing the tungstennitride on the first surface by plasma enhanced chemical vapordeposition using a first reactant gas mixture including WF₆, at leastone of NF₃ and N₂, and H₂, wherein depositing tungsten nitride on thesecond surface by plasma enhanced chemical vapor deposition includesusing a second reactant gas mixture including WF₆, at least one of NF₃and N₂, H₂, and He, and further wherein the partial pressure of WF₆ andthe at least one NF₃ and N₂ used in depositing tungsten nitride on thesecond surface during the second period of time is in the range of about1.5 times to about 20 times the partial pressure of WF₆ and the at leastone NF₃ and N₂ used in depositing the tungsten nitride on the firstsurface during the first period of time.
 11. The method of claim 10,wherein the partial pressure of WF₆ and the at least one NF₃ and N₂ usedin depositing tungsten nitride on the second surface during the secondperiod of time is in the range of about 2 times to about 10 times thepartial pressure of WF₆ and the at least one NF₃ and N₂ used indepositing the tungsten nitride on the first surface during the firstperiod of time.
 12. The method of claim 8, wherein forming tungstennitride on the first surface by plasma enhanced chemical vapordeposition includes biasing the substrate assembly.
 13. The method ofclaim 8, wherein depositing tungsten nitride on the first surface duringthe first period of time by plasma enhanced chemical vapor depositionincludes depositing the tungsten nitride at a substrate temperature in arange of about 200° C. to about 500° C.
 14. The method of claim 13,wherein depositing tungsten nitride on the first surface during thefirst period of time by plasma enhanced chemical vapor depositionincludes depositing the tungsten nitride at a temperature in a range ofabout 250° C. to about 350° C.
 15. The method of claim 12, whereindepositing tungsten nitride on the first surface during the first periodof time by plasma enhanced chemical vapor deposition includes depositingthe tungsten nitride at a deposition pressure in a range of about 0.1torr to about 30 torr.
 16. The method of claim 15, wherein depositingtungsten nitride on the first surface during the first period of time byplasma enhanced chemical vapor deposition includes depositing thetungsten nitride at a deposition pressure in a range of about 0.3 torrto about 3 torr.
 17. The method of claim 7, wherein forming tungstennitride on the first surface during the first period of time includesdepositing tungsten nitride by physical vapor deposition.
 18. The methodof claim 7, wherein depositing tungsten nitride on at least the secondsurface during the second period of time includes depositing tungstennitride by plasma enhanced chemical vapor deposition using a gas mixtureincluding WF₆, at least one of NF₃ and N₂, H₂, and He, wherein thepartial pressure of WF₆ and the at least one of NF₃ is in a range ofabout 0.1 percent to about 20 percent of the total pressure.
 19. Themethod of claim 18, wherein depositing tungsten nitride on at least thesecond surface during the second period of time includes depositingtungsten nitride by plasma enhanced chemical vapor deposition using WF₆,the at least one of NF₃ and N₂, H₂, and He, wherein the partial pressureof WF₆ and the at least one of NF₃ and N₂ is in a range of about 1percent to about 10 percent of the total pressure.
 20. The method ofclaim 18, wherein depositing tungsten nitride on the second surfaceduring the second period of time by plasma enhanced chemical vapordeposition includes depositing the tungsten nitride at a substratetemperature in a range of about 200° C. to about 500° C.
 21. The methodof claim 20, wherein depositing tungsten nitride on the second surfaceduring the second period of time by plasma enhanced chemical vapordeposition includes depositing the tungsten nitride at a temperature ina range of about 300° C. to about 400° C.
 22. The method of claim 7,wherein an opening is defined at least in part by the first and secondsurfaces, the opening being a small high aspect ratio opening having anaspect ratio greater than about 1 and a critical dimension of less thanabout 1 micron.
 23. The method of claim 22, wherein the small highaspect ratio opening has an aspect ratio greater than about 1 and acritical dimension of less than about 0.5 microns.
 24. The method ofclaim 23, wherein the small high aspect ratio opening has an aspectratio greater than about 1 and a critical dimension of less than about0.3 microns.
 25. A method for forming a conformal layer of tungstennitride in an opening defined by a bottom surface and at least one sidewall extending therefrom, the method comprising: depositing tungstennitride on at least the bottom surface by plasma enhanced chemical vapordeposition using a first gas mixture including WF₆, at least one of NF₃and N₂, and H₂; and depositing tungsten nitride on at least the sidewall by plasma enhanced chemical vapor deposition using a secondreactant gas mixture including WF₆, at least one of NF₃ and N₂, H₂, andHe.
 26. The method of claim 25, wherein depositing tungsten nitride onthe bottom surface is performed before the depositing tungsten nitrideon the at least one side wall.
 27. The method of claim 25, wherein thepartial pressure of WF₆ and the at least one of NF₃ and N₂ used indepositing tungsten nitride on the bottom surface is in the range ofabout 1.5 times to about 20 times the partial pressure of WF₆ and the atleast one of NF₃ and N₂ used in depositing the tungsten nitride on theat least one side wall.
 28. The method of claim 25, wherein depositingtungsten nitride on the bottom surface includes biasing a substrateassembly defining the opening.
 29. The method of claim 25, whereindepositing tungsten nitride on the bottom surface includes depositingthe tungsten nitride at a deposition temperature in a range of about200° C. to about 500° C.
 30. The method of claim 25, wherein depositingtungsten nitride on the bottom surface includes depositing the tungstennitride at a deposition pressure in a range of about 0.1 torr to about30 torr.
 31. The method of claim 25, wherein the partial pressure of WF₆and the at least one NF₃ and N₂ used in depositing tungsten nitride onthe at least one side wall is in a range of about 0.1 percent to about20 percent of the total pressure.
 32. The method of claim 31, whereinthe partial pressure of WF₆ and the at least one NF₃ and N₂ is in arange of about 1 percent to about 10 percent of the total pressure whendepositing tungsten nitride on the at least one side wall.
 33. Themethod of claim 31, wherein the partial pressure of He is in a range ofabout 0.5 percent to about 50 percent of the total pressure whendepositing tungsten nitride on the at least one side wall.
 34. Themethod of claim 25, wherein depositing tungsten nitride on the at leastone side wall includes depositing the tungsten nitride at a temperaturein a range of about 200° C. to about 500° C.
 35. The method of claim 25,wherein the opening is a small aspect ratio opening having an aspectratio greater than about 1 micron and a critical dimension of less thanabout 1 micron.
 36. A method for forming tungsten nitride in thefabrication of integrated circuits, the method comprising: providing anopening defined in a substrate assembly, the opening defined by a bottomsurface and at least one side wall extending therefrom; and forming auniform tungsten nitride layer on the bottom surface and the at leastone side wall, wherein the uniform layer is of a thickness in the rangeof about 50 Å to about 500 Å, the step of forming the uniform tungstennitride layer comprising: depositing tungsten nitride on at least thebottom surface by plasma enhanced chemical vapor deposition using afirst gas mixture including WF₆, at least one of NF₃ and N₂, and H₂; anddepositing tungsten nitride on at least the side wall by plasma enhancedchemical vapor deposition using a second reactant gas mixture includingWF₆, at least one of NF₃ and N₂, H₂, and He.
 37. The method of claim 36,wherein depositing tungsten nitride on the bottom surface includesdepositing the tungsten nitride at a temperature in a range of about200° C. to about 500° C. and a deposition pressure in a range of about0.1 torr to about 30 torr.
 38. The method of claim 36, wherein thepartial pressure of WF₆ and the at least one of NF₃ and N₂ is in a rangeof about 0.1 percent to about 20 percent of the total pressure whendepositing tungsten nitride on the at least one side wall.
 39. Themethod of claim 38, wherein the partial pressure of He is in a range ofabout 0.5 percent to about 50 percent of the total pressure whendepositing tungsten nitride on the at least one side wall.
 40. Themethod of claim 39, wherein depositing tungsten nitride on the at leastone side wall includes depositing the tungsten nitride at a temperaturein a range of about 200° C. to about 500° C.
 41. The method of claim 36,wherein the opening is one of a contact opening and a via, the uniformtungsten nitride layer forming a liner thereof, and further wherein theone of the contact opening and via has an aspect ratio greater thanabout 1 micron and a critical dimension of less than about 1 micron. 42.The method of claim 36, wherein the uniform tungsten nitride layer is acapacitor electrode.
 43. A method for use in forming a capacitor, themethod comprising: providing a substrate assembly including an openingdefined therein, wherein the opening is defined by a bottom surface ofthe substrate assembly and at least one side wall extending therefrom;and forming an electrode including a tungsten nitride layer on thebottom surface and the at least one side wall, wherein the layer is of athickness in the range of about 50 Å to about 500 Å, wherein the formingof the tungsten nitride layer comprises: forming tungsten nitride on atleast the bottom surface during a first time period, and depositingtungsten nitride on at least the side wall by plasma enhanced chemicalvapor deposition during a second time period.
 44. The method of claim43, wherein forming tungsten nitride on at least the bottom surfaceduring the first time period includes depositing the tungsten nitride byplasma enhanced chemical vapor deposition using a first gas mixtureincluding WF₆, at least one of NF₃ and N₂, and H₂, and further whereindepositing tungsten nitride on at least the side wall by plasma enhancedchemical vapor deposition during a second time period includes using asecond reactant gas mixture including WF₆, at least one of NF₃ and N₂,H₂, and He.
 45. The method of claim 44, wherein the partial pressure ofWF₆ and the at least one NF₃ and N₂ is in a range of about 0.1 percentto about 20 percent of the total pressure when depositing tungstennitride on the at least one side wall.
 46. The method of claim 45,wherein the partial pressure of He is in a range of about 0.5 percent toabout 50 percent of the total pressure when depositing tungsten nitrideon the at least one side wall.
 47. The method of claim 44, whereindepositing tungsten nitride on the bottom surface includes depositingthe tungsten nitride at a temperature in a range of about 200° C. toabout 500° C. and a deposition pressure in a range of about 0.1 torr toabout 30 torr.
 48. The method of claim 43, wherein the electrode is atop electrode of the capacitor.
 49. The method of claim 43, wherein theelectrode is a bottom electrode of the capacitor.
 50. A method for usein forming an interconnect, the method comprising: providing a substrateassembly having an opening defined therein, the opening defined by abottom conductive surface and at least one side wall extendingtherefrom; and forming an interconnect structure on the bottom surfaceand the at least one side wall, wherein the step of forming theinterconnect structure includes: depositing tungsten nitride on at leastthe bottom surface by plasma enhanced chemical vapor deposition using afirst gas mixture including WF₆, at least one of NF₃ and N₂, and H₂, anddepositing tungsten nitride on at least the side wall by plasma enhancedchemical vapor deposition using a second reactant gas mixture includingWF₆, at least one of NF₃ and N₂, H₂, and He; and forming one or moreadditional conductive materials relative to the tungsten nitride. 51.The method of claim 50, wherein depositing tungsten nitride on thebottom surface includes depositing the tungsten nitride at a temperaturein a range of about 200° C. to about 500° C. and a deposition pressurein a range of about 0.1 torr to about 30 torr.
 52. The method of claim50, wherein the partial pressure of WF₆ and the at least one NF₃ and N₂is in a range of about 0.1 percent to about 20 percent of the totalpressure when depositing tungsten nitride on the at least one side wall.53. The method of claim 52, wherein the partial pressure of He is in arange of about 0.5 percent to about 50 percent of the total pressurewhen depositing tungsten nitride on the at least one side wall.
 54. Themethod of claim 53, wherein depositing tungsten nitride on the at leastone side wall includes depositing the tungsten nitride at a temperaturein a range of about 200° C. to about 500° C.
 55. The method of claim 50,wherein the opening is one of a contact opening and a via, the one ofthe contact opening and via having an aspect ratio greater than 1 micronand a critical dimension of less than 1 micron, and further wherein thetungsten nitride is formed of a thickness in a range of about 50 Å toabout 500 Å.
 56. A method for forming tungsten nitride in thefabrication of integrated circuits, the method comprising: providing asubstrate assembly including at least a generally horizontal firstsurface and a second surface extending therefrom; forming tungstennitride on at least the horizontal first surface during a first periodof time; and depositing tungsten nitride on at least the second surfaceduring a second period of time by chemical vapor deposition, wherein thedeposition of tungsten nitride on at least the second surface includesproviding a reactant gas mixture and subjecting the reactant gas mixtureto a glow discharge created by applying an electromagnetic field acrossthe reactant gas mixture.
 57. The method of claim 56, wherein depositingtungsten nitride on at least the second surface during the second periodof time includes depositing tungsten nitride by chemical vapordeposition using a reactant gas mixture including WF₆, at least one ofNF₃ and N₂, H₂, and He, wherein the partial pressure of WF₆ and the atleast one of NF₃ and N₂ is in a range of about 0.1 percent to about 20percent of the total pressure.
 58. The method of claim 57, wherein theglow discharge is created by applying a radio frequency electromagneticfield of 13.56 megahertz at a power density of about 0.1 W/cm² to aboutto about 2 W/cm² across the reactant gas mixture.
 59. The method ofclaim 57, wherein depositing tungsten nitride on the second surfaceduring the second period of time by chemical vapor deposition includesdepositing the tungsten nitride at a substrate temperature in a range ofabout 200° C. to about 500° C. and at a deposition pressure in a rangeof about 0.1 torr to about 30 torr.
 60. The method of claim 56, whereinforming tungsten nitride on at least the horizontal first surfaceincludes depositing the tungsten nitride on the first surface bychemical vapor deposition, wherein depositing tungsten nitride on atleast the horizontal first surface includes providing a reactant gasmixture and subjecting the reactant gas mixture to a glow dischargecreated by applying an electromagnetic field across the reactant gasmixture.
 61. The method of claim 60, wherein the glow discharge for usein forming tungsten nitride on at least the horizontal first surface iscreated by applying a radio frequency electromagnetic field of 13.56megahertz at a power density of about 0.1 W/cm² to about to about 2W/cm² across the reactant gas mixture.
 62. The method of claim 61,wherein depositing tungsten nitride on the first surface during thefirst period of time by chemical vapor deposition includes depositingthe tungsten nitride at a substrate temperature in a range of about 200°C. to about 500° C. and at a deposition pressure in a range of about 0.1torr to about 30 torr.
 63. The method of claim 60, wherein formingtungsten nitride on the first surface includes depositing the tungstennitride on the first surface by chemical vapor deposition using a firstreactant gas mixture including WF₆, at least one of NF₃ and N₂, and H₂,wherein depositing tungsten nitride on the second surface by chemicalvapor deposition includes using a second reactant gas mixture includingWF₆, at least one of NF₃ and N₂,H₂, and He, and further wherein thepartial pressure of WF₆ and the at least one NF₃ and N₂ used indepositing tungsten nitride on the second surface during the secondperiod of time is in the range of about 1.5 times to about 20 times thepartial pressure of WF₆ and the at least one NF₃ and N₂ used indepositing the tungsten nitride on the first surface during the firstperiod of time.
 64. A method for forming a conformal layer of tungstennitride in an opening defined by a bottom surface and at least one sidewall extending therefrom, the method comprising: depositing tungstennitride on at least the bottom surface by chemical vapor depositionusing a first gas mixture including WF₆, at least one of NF₃ and N₂, andH₂, wherein depositing tungsten nitride on at least the bottom surfaceincludes subjecting the first gas mixture to a glow discharge created byapplying an electromagnetic field across the first gas mixture; anddepositing tungsten nitride on at least the side wall by chemical vapordeposition using a second gas mixture including WF₆, at least one of NF₃and N₂, H₂, and He, wherein depositing tungsten nitride on at least theside wall includes subjecting the second gas mixture to a glow dischargecreated by applying an electromagnetic field across the second gasmixture.
 65. The method of claim 64, wherein the partial pressure of WF₆and the at least one of NF₃ and N₂ used in depositing tungsten nitrideon the bottom surface is in the range of about 1.5 times to about 20times the partial pressure of WF₆ and the at least one of NF₃ and N₂used in depositing the tungsten nitride on the at least one side wall.66. The method of claim 64, wherein depositing tungsten nitride on thebottom surface includes depositing the tungsten nitride at a depositiontemperature in a range of about 200° C. to about 500° C. and adeposition pressure in a range of about 0.1 torr to about 30 torr, andfurther wherein the glow discharge is created by applying a radiofrequency electromagnetic field of 13.56 megahertz at a power density ofabout 0.1 W/cm² to about to about 2 W/cm².
 67. The method of claim 64,wherein depositing tungsten nitride on the at least one side wallincludes depositing the tungsten nitride at a temperature in a range ofabout 200° C. to about 500° C. and a deposition pressure in a range ofabout 0.1 torr to about 30 torr, and further wherein the glow dischargefor use in forming tungsten nitride on the at least one side wall iscreated by applying a radio frequency electromagnetic field of 13.56megahertz at a power density of about 0.1 W/cm² to about to about 2W/cm².
 68. The method of claim 64, wherein the partial pressure of WF₆and the at least one NF₃ and N₂ used in depositing tungsten nitride onthe at least one side wall is in a range of about 0.1 percent to about20 percent of the total pressure.
 69. The method of claim 68, whereinthe partial pressure of He is in a range of about 0.5 percent to about50 percent of the total pressure when depositing tungsten nitride on theat least one side wall.
 70. A method for forming a conformal conductivelayer in the fabrication of integrated circuits, the method comprising:providing a substrate assembly including at least a generally horizontalfirst surface and a second surface extending therefrom; forming a firstportion of the conductive layer on at least the horizontal first surfaceduring a first period of time; and depositing a second portion of theconductive layer on at least the second surface during a second periodof time, wherein the second period of time is different than the firstperiod of time, and further wherein depositing the second portion of theconductive layer on at least the second surface includes providing areactant gas mixture and subjecting the reactant gas mixture to a glowdischarge created by applying an electromagnetic field across thereactant gas mixture.
 71. The method of claim 70, wherein an opening isdefined at least in part by the first and second surfaces, the openingbeing a small high aspect ratio opening having an aspect ratio greaterthan about 1 and a critical dimension of less than about 1 micron. 72.The method of claim 70, wherein forming the first portion of theconductive layer on at least the horizontal first surface is performedafter the depositing of the second portion of the conductive layer on atleast the second surface.
 73. The method of claim 70, wherein formingthe first portion of the conductive layer on at least the horizontalfirst surface includes depositing the first portion of the conductivelayer on at least the horizontal first surface by plasma enhancedchemical vapor deposition.
 74. The method of claim 73, whereindepositing the second portion of the conductive layer on at least thesecond surface includes depositing a second portion of the conductivelayer on at least the second surface by plasma enhanced chemical vapordeposition using a reactant gas mixture including helium.
 75. The methodof claim 74, wherein forming the first portion of the conductive layeron at least the horizontal first surface includes depositing tungstennitride on the horizontal first surface by plasma enhanced chemicalvapor deposition using a first reactant gas mixture including WF₆, atleast one of NF₃ and N₂, and H₂, wherein depositing a second portion ofthe conductive layer on the second surface includes depositing tungstennitride on the second surface by plasma enhanced chemical vapordeposition using a second reactant gas mixture including WF₆, at leastone of NF₃ and N₂, H₂, and He, and further wherein the partial pressureof WF₆ and the at least one of NF₃ and N₂ used in depositing tungstennitride on the second surface during the second period of time is in therange of about 1.5 times to about 20 times the partial pressure of WF₆and the at least one NF₃ and N₂ used in depositing the tungsten nitrideon the horizontal first surface during the first period of time.
 76. Themethod of claim 75, wherein the partial pressure of WF₆ and the at leastone of NF₃ and N₂used in depositing tungsten nitride on the secondsurface during the second period of time is in the range of about 2times to about 10 times the partial pressure of WF₆ and the at least oneof NF₃ and N₂ used in depositing the tungsten nitride on the horizontalfirst surface during the first period of time.
 77. The method of claim70, wherein forming the first portion of the conductive layer on atleast the horizontal first surface includes depositing the first portionof the conductive layer on at least the horizontal first surface byphysical vapor deposition.
 78. The method of claim 71, wherein theopening is one of a contact opening and a via, and further wherein theconductive layer forms a liner thereof.
 79. A method for forming aconformal insulative layer in the fabrication of integrated circuits,the method comprising: providing a substrate assembly including at leasta generally horizontal first surface and a second surface extendingtherefrom; forming a first portion of the insulative layer on at leastthe horizontal first surface during a first period of time; anddepositing a second portion of the insulative layer on at least thesecond surface during a second period of time, wherein the second periodof time is different than the first period of time, and further whereindepositing the second portion of the insulative layer on at least thesecond surface includes providing a reactant gas mixture and subjectingthe reactant gas mixture to a glow discharge created by applying anelectromagnetic field across the reactant gas mixture.
 80. The method ofclaim 79, wherein an opening is defined at least in part by the firstand second surfaces, the opening being a small high aspect ratio openinghaving an aspect ratio greater than about 1 and a critical dimension ofless than about 1 micron.
 81. The method of claim 79, wherein formingthe first portion of the insulative layer on at least the horizontalfirst surface is performed after the depositing of the second portion ofthe insulative layer on at least the second surface.
 82. The method ofclaim 79, wherein forming the first portion of the insulative layer onat least the horizontal first surface includes depositing the firstportion of the insulative layer on at least the horizontal first surfaceby plasma enhanced chemical vapor deposition under a first set ofconditions.
 83. The method of claim 82, wherein depositing a secondportion of the insulative layer on at least the second surface includesdepositing a second portion of the insulative layer on at least thesecond surface by plasma enhanced chemical vapor deposition under asecond set of conditions that are different than the first set ofconditions.
 84. The method of claim 79, wherein the insulative layercomprises an oxide material.
 85. The method of claim 84, wherein theoxide material comprises silicon oxide.
 86. The method of claim 79,wherein the insulative layer comprises silicon nitride.